Syringe pipette



Patented Aug. 19, 1952 we 7 y SYBINGE PIPETTE y f Landon -ver, Roanoke, Va., assignor to: I

American Viscose Corporation, Wilmington, DeL, a corporation of Delaware This invention relates to an improved syringe pipet-and is particularly concerned with a modification-thereof adapted to facilitate the accurate measurement of repeated doses or samples, espe'cially of the same volume. a I a a It is" an object of theinvention to providea simple attachmentwhich can be applied to many standardforms of-hypodermic syringes to modify them'to serve the purposes of the present invention: It is also an object 'of the invention to provide a form of syringe pipetof'simple con struction which will facilitate the accurate measurement of repeated 'doses or-sa'mples. ..-It is also an obje'ct of the invention toprovide an improved plunger adapted to cooperate with the calibrated cylinder of many standard forms of syringes for serving the purposes of the invention;- Other-objects and advantages of the invention will be apparent from the drawing and the descriptionthereof hereinafter.

Inthe' drawing:

Figure 1 is a side view of a. preferred embodiment of theinvention in which the modification of the invention takes the'form of .an attachment applicable to standard syringes.

Figure 2 is a section taken on. line II1I of Figureil; V

Figure-3is a similar section but showing a different positional relationship of the parts, and.

Figure 4 is a modification showing a system for deaeration of' the contents of the pipet.

- As shown in the embodiment of Figures 1 to 3, the. syringe pipet comprises a mainbody havthe cylinder is necked down abruptly at 4 and is connected to a conduit 5, which may be any suitable needle such as a'No. l8 guage stainless steelneedle, which is attached to the cylinder by the coupling 6. v t

The cylinder is provided with a member I which, projects outwardly from its body at any pointf' along itself. Preferably, as shown, this member 1 takes the form of a flange at the end of'thejcylinder 3 into "which the plunger 8 enters. As shown, the member .1 may be integral with the cylinder 3'which may be made either of a transparent or opaque material, such as glass, plastics, or stainless steel. If of an opaque material, the calibrations 9 may be omitted sincethey serve no'purpose in such-a case." Themember I has a portion along one side Ill 'which is ':of reduced external radius or is completely omittedto make it possible for parts of'the attachment to pass freely beyond the member I when such parts arerotated intoproper position with respect tliere'to.

Application May 2, 1951, Serial No. 224, 13 .13 Claims. (01. 128-218) The plunger 8 has an outside cylindrical diameter which is complementary to and fits slidingly within the internal cylindrical wall of the cylinder 3. Whilethe plunger may be solid, it may also be formed'of a hollow cylindrical tube terminating in a closed end II. Guard means comprising a rod I2 is secured to the plunger at a point thereon beyond any portion thereof adapted to extend intothe cylinder 3. The rod l2 has a laterally projecting portion l3 which may extend arcuatelyand. concentrically; or approximately so, aboutaportion of the cylinder 3. This guard means serves to abut against the.

member I to prevent thereby the plunger .8 from being accidentally withdrawn entirely from the cylinder 3. Preferably, the member 1 extends outwardly from the cylinder 3 onboth sides of the ambit of motion of rod 12 so as to limit the rotation of the plunger'relative to the cylinder 3 whereby the terminal end I4: of the projecting .ing a calibrated hollow cylinder 3. lQne end of portion I3 of the guard rod cannot be moved out of the way of flange l unintentionally. However, the rod I2 may be made of a. sprin y, resilient material to enable'one to spring the end I4 outwardly in order to take the pipet apart for clean.- ing.

Control means comprising a rod l5'is also secured to the plunger. This rod I5 may simply extend parallel to the major portion of rod I 2 and is positioned radially outwardly from the plunger a distance which enables it to be moved past the portion' ll] of memberlbut not so far out from the center of the plunger that when the plunger is rotated into the relative position shown in Figure 3 the rod l5 can escape the pro- J'ection'L h .m p

The guard means I2 and control means I5 may .be secured to-the plunger '8 by any suitable means. As shown, the plunger is provided with an integral outwardly extendingfiange I6' to which the ring I! may be secured by means of a plug is which is threaded into" a recess formed in the ring I1. The rods I2 and I5 may then simply be press-fitted into suitable bores I9 and 20 in the ring ll. While the ring I I isshown secured to the plunger in the preferred end position thereof, that is, on the outer end of the plunger, it may be secured to the plunger away from the end thereof providedit is on a portion of the plunger which is outside of the cylinder 3 when the plunger 'is-inser'tedto the maximum extent therein.

When the member; 1115' a symmetricalfflange with two flattened sides as 'clearlyshown'in' Figure 2, it may be desirable to assemble the plunger and cylinder in the same relative positions every time the instrument is used to obtain the most precise measurements repeatedly. This may be to be secured to a flange lt-on any standard plunger of a conventional hypodermic syringe, h

it is within the scope of the invention to form a somewhat larger flange integrally with the plunger, 8 into which the rods l2 and I5 may be secured in any suitable fashion, such as by'press' fitting or screw threading, asshown in the next In Figure 4, a modification is shown in which embodiment.

the member 1a (corresponding to the member in Figures 1 to 3) is either integral on the cylin der 3 or suitably secured thereon but in any event is fixed at a position'away from the end of the cylinder .3. The guard means l2 may be a'rod extending from a threaded stud 2| which is screwed into a suitable bore in a flange or flanged head 22 of the plunger 8a. Similarly, rod 15 extends: from a stud 23 which threadedly engages a suitable bore in'the. flanged head 22. By the use of the threaded, stud attachments for rods I2 and 15, the system is readily adapted to the substitution of rods of different length to provide any desired predetermined sample volume. In operation, the needle of the syringe 'pipet is introduced into the liquid to be sampled or to be measured while the plunger is inserted all the way within the cylinder 3. Liquid is then sucked into the cylinder 3 by withdrawal of the plunger 8 or8a until the end ['4 of rod I2 engages the member I or "M. The plungerof the pipet occupies the: relative position with respect to the member 1 shown in Figure 2 up'to this stage. 1

The next'operation, if no bubbles have been introduced during the withdrawal of the plunger, is to rotate the'plunger relative to the cylinder into the position of Figure 3 and to move the plunger forward until .the control rod [5 abuts against the member I or Ia. This may be done before or after withdrawal of the discharge conduit -5 from the body of liquid being sampled. Thereafter, the liquid may be ejected into any desired container by merely rotating the plunger sampled and held in a vertical position with conduit 5 directed upward and tapped to cause the bubbles to rise upwardly. Then the plunger 8 or 8a is rotated relative to the cylinder 3, into the position of Figure '3, and moved vertically upward into the cylinder until the control rod I5 abuts against flange member 1 or la, in order to discharge any air bubbles along with the excess liquid. At the same time, the discharge conduit 5 is preferably inserted loosely into the tapered opening 24 of a tube 25 of suitable bore to which suction is applied while the bubbles and excess liquid are being discharged. The excess liquid may thus be drawn off into a suitable container withoutjspilling over the outside of the pipet where'it might causeinconvenience or injury to the operator. The use of the suction may or may not be accompanied by tapping of the cylinder. A loose fit between the end of the discharge conduit 5 and the tapered opening 24 of tube 25 is usually preferable to a tight one, since in the latter case the application of too strong a suction may actuallyintroduce more bubbles into the pipet. After "the bubbles and exee'ss liquid have been removed as described above, the sample may :be ejected into any suitable container, as in the previous case.

It is to be understood that changes and variationsmay be made; without departing from the spirit andscdpe .of the invention as defined in V the appendedclaims.

I claim: 1

1. A syringe pipet comprising a hollow cylinder forcontaining a liquid to be measured, a conduit communicating with one end of the cylinder for introductionand discharge of liquid, a member projecting laterally fromthe cylinder, a plunger reciprocably and rotatably mounted in the cylinder for introducing and displacing liquid with respect to the cylinder,,-guard means secured to the plunger and extending along the cylinder for engaging the laterally extending member to prevent accidental complete withdrawal of the plunger from the cylinder, and

control means secured'to the plunger for engaging the member to predeterm-ine the position of the plunger within the cylinder. v 7 n V 2. A pipet as defined in ,claim 1 in whichthe guard means and control means are secured to the head of the plunger at the end thereof outside of the cylinder.

-3. A pipet as defined in claim 1 in which the guard means comprises arod extending alongside the plunger which has a laterally extending portion extending alongside the cylinder and adapted to engage the laterally projecting member on the cylinder. 7

4. A pipet as defined in claim lin which the guard means comprises a'rod extending alongside the plunger whichhas a laterally extending portion I extending alo'ng'si'de the cylinder and adapted to engage the laterally projecting-member on the cylinder and the controlmean'seomtending' radially outwarmyrrom tne"cylinder dif- 55 1 ferentdistanc'es.

guard means comprises a rod-extending along- 6. A pipet as-defi'nedfinclaim l in which "the side "the plunger and having laterally extending portion extending alongside thecylinder and adapted to engage the laterally projecting mem- "ber on the cylinderandthecoritrolimeanscomprises a rod shorter tharnand extending alongside, the first-mentioned 'rod and, in which "the laterally projecting member is a flange integral with the cylinder having 'adj'acentportibns extending radially'outwardly from the cylinder different distances.

'7. A pipet as defined in .claimtin'iwhich the fiangeonthe cylinder'is disposed at "theextrem'e nd thereof away fromthe conduit. 7

'8; An attachment for a syringelpipet tem esing a ring 'adapt'ed'to besecuredto a fiange on the portion-of the plunger of said pipet which is outside the main cylinder thereof, a pair of rods extending generally axially from said ring-,said

rods being of different lengths, the longer of the rods having a laterally projecting portion.

9. An attachment as defined in claim 8 in which the laterally projecting portion of the longer rod extends generally arcuately about the axis of the ring substantially in a plane extending at right angles to the axis of said ring.

10. As an article of manufacture, a plunger for a syringe pipet, said plunger having a cylindrical outer wall adapted to fit slidingly within the inside wall of the cylinder of a pipet, a ring on a portion of the plunger which is to be outside the cylinder at all times, a pair of elements secured to the ring, disposed radially outwardly from the plunger, and extending alongside the plunger, one of said elements being longer than the other and having a laterally projecting portion spaced farther from the ring than the end of the other element.

11. An article of manufacture as defined in claim 10 in which said laterally projecting portion is disposed substantially in a plane at right angles to the axis of the plunger.

12. An article of manufacture as defined in claim 11 in which said elements consist of generally parallel rods extending approximately parallel to the axis of the plunger and in which said laterally projecting portion is of arcuate shape and approximately concentric with respect to the axis of the plunger.

13. A syringe pipet comprising a hollow cylinder for containing a liquid to be measured, a conduitcommunicating with one end of the cylinder for introduction and discharge of liquid, a member projecting laterally from the cylinder of such a shape that a control means attached to a plunger sliding within the cylinder can be made to engage or pass at will the said laterally projecting member, a plunger reciprocably and rotatably mounted in the cylinder for introducing and displacing liquid with respect to the cylinder, guard means secured to the plunger and extending along the cylinder for engaging the lat erally extending member to prevent accidental complete withdrawal of the plunger from the cylinder, and control means secured to the plunger for engaging the aforesaid laterally extending member to predetermine the position of the plunger within the cylinder.

' LANDON A. SARVER.

No references cited. 

